[Prenatal diagnosis of fetal chromosomal aneuploidies using quantitative fluorescent PCR (QF-PCR)]. / Wykorzystanie ilosciowej fluorescencyjnej techniki PCR (QF-PCR) w diagnozowaniu wybranych aneuploidii chromosomowych u plodu.

The trisomy of the 21 chromosomes is one of the most important chromosomal anomalies and is responsible for Down syndrome. It persists in Poland in 1/700 birth. The risk of childbirth with Down syndrome grows with age, especially in women after 35 years old. In this study we performed QF-PCR method with specific polymorphic sequence--D21S11 for detection of trisomy of the 21 chromosome. DNA for PCR was isolated from amniotic fluid, blood of healthy and with Down syndrome patients. PCR was performed with ProfilerPlus Kit, which permits for amplification of 9 STR loci (also D21S11) and gender marker--amelogenin gene. We detected incorrect amplification of STR sequence for D21S11 in one amniotic fluid, which was confirmed by kariotyping as trisomy of the 21 chromosome of fetus.

Early stress and chronic methylphenidate cross-sensitize dopaminergic responses in the adolescent medial prefrontal cortex and nucleus accumbens.

Methylphenidate (MP) is widely used to treat attention deficit/hyperactivity disorder in children. However, basic research has been mainly focused on MP treatment in adult, behaviorally normal rodents. Here we analyzed MP-evoked changes of dopamine (DA) release in the limbic system of juvenile rodents with hyperactive and attention deficit-like symptoms. Using dual probe in vivo microdialysis, DA levels were quantified in the medial prefrontal cortex and nucleus accumbens of juvenile and adolescent degus (Octodon degus). Acute stress- and acute MP-evoked dopaminergic responses in normal juvenile and adolescent animals were compared with (i) animals showing symptoms of hyperactivity and attention deficits induced by early life stress, i.e. repeated parental separation during the first 3 weeks of life, and (ii) animals chronically treated with MP during pre-adolescence. Our main results revealed that (i) early life stress and (ii) chronic MP treatment during pre-adolescence cross-sensitize limbic dopaminergic functions in adolescent animals. Furthermore, we demonstrated a unique pattern of acute MP-evoked DA release in the juvenile compared with the adolescent medial prefrontal cortex and nucleus accumbens. Our findings that the functional maturation of dopaminergic limbic function is significantly altered by early life experience, i.e. repeated parental separation and chronic MP treatment, allow novel insights into the etiology of attention deficit/hyperactivity disorder and into the long-term consequences of MP treatment on brain development.

Epigenetic modulation of the developing serotonergic neurotransmission in the semi-precocial rodent Octodon degus.

Environmental influences during early life periods, particularly those provided by the mother or parents, are generally considered to have a strong impact on the development of brain and behaviour of the offspring. In the semi-precocial South American species Octodon degus, a rodent becoming increasingly popular in different laboratory research fields, the present study aimed to examine the consequences of the disturbance of the parent-offspring interaction induced by parental separation on the serotonergic neurotransmission. Based on a quantitative neurochemical approach using brain homogenates obtained from cortical regions and the hippocampus our results revealed that (i) the tissue levels of serotonin and 5-hydroxyindoleacetic acid showed in both sexes a moderate, around two-fold increase until adulthood, indicating relatively matured cortical and hippocampal serotonergic systems at birth. In addition, we found an age-, region- and sex-specific pattern of changes in the serotonergic system induced by (ii) an acute stress challenge early in life (1-h parental separation at the postnatal day 3, 8, 14 or 21) with the most pronounced effects at earlier ages (between postnatal days 3 and 14) in the female cortex and (iii) repeated stress exposure (1h daily) during the first 3 weeks of life affecting cortical regions of both sexes. Taken together, these data indicate that early life stress (i.e. parental separation) influences the developing serotonergic system in the semi-precocial O. degus, even if the brain is relatively well matured at the early stages of postnatal development.

Electronic coupling between base pair dimers of LNA:DNA oligomers.

We calculated ab initio electronic coupling elements between neighboring base-pair dimers in a set of LNA:DNA oligomers with different numbers of locked nucleotides and compared them by averaging the values over ensembles of snapshots from molecular dynamics trajectories. Averaging was based on coupling elements for various ensembles comprising of 33,000 structures. The known pronounced variations of coupling elements on the nanosecond timescale due to thermal fluctuations of the DNA structure were confirmed. We found significant differences in electronic coupling at the dimer level between a non-modified DNA:DNA duplex and the corresponding duplex containing one fully LNA-substituted strand. We rationalized these differences by very dissimilar overlap in the pi-stack as a consequence of the LNA-modified system approximating an A-DNA-type helix. The calculated coupling elements for the non-modified reference duplex were similar to those of standard B-DNA and those for the fully modified oligomer resembled the matrix elements estimated for standard A-DNA.

Methylphenidate treatment recovers stress-induced elevated dendritic spine densities in the rodent dorsal anterior cingulate cortex.

Exposing pups of the rodent species Octodon degus to periodic separation stress during the first three postnatal weeks leads to behavioral alterations, which include reduced attention towards an emotional stimulus and motoric hyperactivity. These behavioral changes, which are reminiscent of symptoms of attention deficit hyperactivity disorder (ADHD), are paralleled by synaptic changes in the dorsal anterior cingulate cortex (ACd), a limbic cortex region, which plays a key role in the modulation of attentional and executive functions. ADHD is typically treated with methylphenidate (MP), a drug acting on the dopaminergic system. However, the effect of chronic MP-treatment on neuronal and synaptic maturation in the developing brain is unknown. Applying the Golgi-Cox stainining technique, we tested in which way chronic MP-treatment interferes with dendritic and synaptic development in the ACd and whether this treatment can restore the stress-induced changes of neuronal connectivity. We found that chronic treatment with 1 mg/kg MP recovers stress-induced changes of spine densities in the ACd. Furthermore, MP-treatment resulted in increased dendritic length and complexity in both, stressed as well as unstressed control animals. These results indicate that synaptic reorganization as well as dendritic growth in the prefrontal cortex continue into prepuberty and are modulated by MP-treatment.

Structure of rhodamine 6G-DNA complexes from molecular dynamics simulations.

Chromophore-DNA complexes are useful for understanding charge transport along pi-stacks once their structural properties have been clarified. We studied two rhodamine 6G semicapping complexes with 15-mer B-DNA duplexes to determine the preferred orientation of the dye with respect to the neighboring base pair. For each of these systems, two distinct chromophore alignments were identified and quantified in terms of base-step parameters. The obtained geometries agree well with those derived from an NMR structure refinement of similar complexes. Cross-correlation analysis of the base-step parameters shows that slide and twist are highly interdependent during the structural transition from one conformation to the other.